Streak apparatuses are for converting the temporal intensity distribution of to-be-measured light into a spatial intensity distribution on an output screen (refer to Patent Documents 1 and 2, for example). In such streak apparatuses, to-be-measured light first enters a photoelectric surface provided at one end of a streak tube. Then, acceleration electrodes accelerate a group of photoelectrons emitted from the photoelectric surface in accordance with the intensity of the to-be-measured light to cause them to travel toward a fluorescent screen provided at the other end of the streak tube.
In the streak tube, there are provided deflection electrodes composed of a pair of electrodes facing each other across the tube axis between the photoelectric surface and the fluorescent screen. Then, a deflection voltage is applied to the group of photoelectrons emitted from the photoelectric surface when passing between the deflection electrodes. This causes the group of photoelectrons to be deflected at different angles in the direction approximately perpendicular to the tube axis to enter the fluorescent screen and then to form a so-called streak image. Thus, the change in brightness in the sweep direction of the streak image shows the temporal change in the intensity of the to-be-measured light that enters the photoelectric surface.    Patent Document 1: Japanese Patent Publication No. H04-79465    Patent Document 2: Japanese Patent Publication No. H04-73257